1. Field of the Invention
The present invention pertains to the production of chlorocarbons, or more particularly to the continuous production of telomers of the type having the formula CCl.sub.3 (CH.sub.2 CCl.sub.2).sub.n Cl where n=1-3 (Formula I) by the continuous reaction of CCl.sub.4 and vinylidene chloride. Such compounds are useful intermediates for the production of hydrofluorocarbons such as CF.sub.3 CH.sub.2 CF.sub.2 H and CF.sub.3 CH.sub.2 CF.sub.2 CH.sub.2 CF.sub.3. The latter find use as non-ozone depleting blowing agents and non-ozone depleting cleaning solvents respectively.
2. Description of the Prior Art
The preparation of compounds of Formula I is not new. They have been prepared by the reaction of CCl.sub.4 with vinylidene chloride using metallic salts or organic free radical initiators as a catalyst. However, all prior methods for the preparation of Formula I compounds require a batch reactor process. In this regard, U.S. Pat. No. 5,395,997, which is incorporated herein by reference, teaches the production of a mixture of telomers which must be separated by distillation.
Because vinylidene chloride is volatile and the addition of CCl.sub.4 to vinylidene chloride is slow, such reactions are typically conducted under pressure and at temperatures of about 80.degree.-150.degree. C. Such a process is inefficient for the manufacture of large quantities since considerable time is spent cooling and removing the product mixture, recharging raw materials, and heating the reactants.
A problem in the art of preparing compounds of Formula I compounds is the control of the telomer distribution. While it is less difficult to limit n to 1, since CCl.sub.4 is more reactive than the 3-carbon telomer, CCl.sub.3 CH.sub.2 CCl.sub.3, it is much more difficult to stop at n=2 since the reactivity of the 3-carbon and 5-carbon telomers are approximately the same. The same is true of the 5-carbon vs. the 7-carbon telomers. Control of the reaction to give essentially only one telomer has not been readily achieved heretofore. It has been particularly difficult to achieve reaction control at suitable conversions of the reactants. Thus, when only the 5-carbon telomer has been desired, practical large scale preparations have been severely limited by low conversions due to relative reactivities and low reactor throughput due to the batch type process.
The present invention provides a means of increasing the efficiency of the manufacturing process for Formula I compounds, and provides a means for obtaining substantially only the 3-carbon, 5-carbon or 7-carbon telomer.